The ingredient is only one variable.
Relevant variables include the chemical form, concentration, pH, vehicle, stability, packaging, contact time, application area, and storage. A study of one preparation should not automatically be assigned to another.
Delivery studies answer narrow questions.
Laboratory skin-penetration experiments can describe movement under controlled conditions. They do not automatically establish the behavior, safety, or visible result of a different commercial formula used at home.
A better comparison question.
Instead of asking whether an ingredient “works,” ask: what exact preparation was studied, in what model or population, at what amount and schedule, with what endpoint, and how closely does it match the finished product?
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Selected authoritative sources
These sources are provided so you can inspect the study type, molecule, route, and limitations directly. They do not endorse a VitaPep product.